1 /*
2 * DMA mapping support for platforms lacking IOMMUs.
3 *
4 * Copyright (C) 2009 Paul Mundt
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 */
10 #include <linux/dma-mapping.h>
11 #include <linux/io.h>
12
nommu_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction dir,unsigned long attrs)13 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
14 unsigned long offset, size_t size,
15 enum dma_data_direction dir,
16 unsigned long attrs)
17 {
18 dma_addr_t addr = page_to_phys(page) + offset;
19
20 WARN_ON(size == 0);
21
22 if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
23 dma_cache_sync(dev, page_address(page) + offset, size, dir);
24
25 return addr;
26 }
27
nommu_map_sg(struct device * dev,struct scatterlist * sg,int nents,enum dma_data_direction dir,unsigned long attrs)28 static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
29 int nents, enum dma_data_direction dir,
30 unsigned long attrs)
31 {
32 struct scatterlist *s;
33 int i;
34
35 WARN_ON(nents == 0 || sg[0].length == 0);
36
37 for_each_sg(sg, s, nents, i) {
38 BUG_ON(!sg_page(s));
39
40 if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
41 dma_cache_sync(dev, sg_virt(s), s->length, dir);
42
43 s->dma_address = sg_phys(s);
44 s->dma_length = s->length;
45 }
46
47 return nents;
48 }
49
50 #ifdef CONFIG_DMA_NONCOHERENT
nommu_sync_single(struct device * dev,dma_addr_t addr,size_t size,enum dma_data_direction dir)51 static void nommu_sync_single(struct device *dev, dma_addr_t addr,
52 size_t size, enum dma_data_direction dir)
53 {
54 dma_cache_sync(dev, phys_to_virt(addr), size, dir);
55 }
56
nommu_sync_sg(struct device * dev,struct scatterlist * sg,int nelems,enum dma_data_direction dir)57 static void nommu_sync_sg(struct device *dev, struct scatterlist *sg,
58 int nelems, enum dma_data_direction dir)
59 {
60 struct scatterlist *s;
61 int i;
62
63 for_each_sg(sg, s, nelems, i)
64 dma_cache_sync(dev, sg_virt(s), s->length, dir);
65 }
66 #endif
67
68 const struct dma_map_ops nommu_dma_ops = {
69 .alloc = dma_generic_alloc_coherent,
70 .free = dma_generic_free_coherent,
71 .map_page = nommu_map_page,
72 .map_sg = nommu_map_sg,
73 #ifdef CONFIG_DMA_NONCOHERENT
74 .sync_single_for_device = nommu_sync_single,
75 .sync_sg_for_device = nommu_sync_sg,
76 #endif
77 .is_phys = 1,
78 };
79
no_iommu_init(void)80 void __init no_iommu_init(void)
81 {
82 if (dma_ops)
83 return;
84 dma_ops = &nommu_dma_ops;
85 }
86